This invention relates to an improved bell actuating mechanism. More specifically, this invention relates to an improved bell actuating mechanism in the combination of a spring driven motor having a winding shaft which rotates less than one complete revolution during the unwinding of the motor from a fully wound condition, escapement means for permitting the motor to unwind at a controlled rate and a bell to be struck immediately proximate to completion of unwinding of the motor.
Spring wound timer motors provided with bells are common. Many include complicated mechanisms. Some such mechanims have desirable features. However, they suffer the disadvantage of being relatively complex and, consequently, relatively expensive. In particular, a simple, reliable, inexpensive bell actuating mechanism for such devices is highly desired.
Typical of the prior art devices are those of U.S. Pat. Nos. 491,328, 2,583,245, 3,827,232 and 4,020,625.
In the alarm clock of U.S. Pat. No. 491,328, when the bell is turned in the direction in which the numbers increase, it will, when released, return to its first position, and the movement is so timed that it will take five minutes to return from the five marking, ten minutes from the ten marking and so on. Upon the return of the bell to its first or zero position, a hammer carried by a lever, pivoted to the base, is thrown toward the bell by means of a coiled spring. The lever and, consequently, the hammer, is actuated by engagement of a lug mounted upon the bell. The lug is hinged to the bell so that in winding up the bell, the lug may yield to pass over the lever but upon the return will bear forceably against the lever. While less complicated than some devices, this is a relatively expensive construction.
In the timing device of U.S. Pat. No. 2,583,245, when a pointer reaches the zero position, a shoulder defined by a sharp radial edge of the shoulder of a disc is disposed adjacent to a pin and permits the pin to drop off the sharp corner into notches of timing discs, the notches then being substantially aligned. This causes a lever to move under the biasing influence of a spring and impinge upon a clapper against a bell. This is a rather complicated and expensive arrangement.
In the spring driven timer of U.S. Pat. No. 3,827,232, at the end of the selected interval, a notch becomes aligned with a pin and a bellcrank is quickly rotated. As the bellcrank rotates, a foot supported thereon engages a hammer supported on a stud extending between upper and lower frame plates. A spring is wound about the stud and has one end hooked around the hammer and the other end trapped behind a leg, to maintain the hammer rotated fully in its counterclockwise direction against the foot. When the bellcrank rotates in a counterclockwise direction, the foot bears against the hammer, urging it in a clockwise direction, and causing it to rotate about its stud sharply against the inner surface of the bell. In this manner the bell is caused to sound when a timing cam has reached a certain position. This arrangement provides a ringing of longer duration than a single striking. This is achieved, however, only by means of a considerably complicated and expensive construction.
In the expanded scale timer of U.S. Pat. No. 4,020,625, a cam rotates in a counterclockwise direction until a drop surface of a notch moves under a follower and allows the follower to drop into the notch with a snap action under the influence of a biasing spring. This snap action develops considerable momentum in a relatively heavy lever and when the lever impacts on a stop, the momentum causes the lever to pivot about the stop and take up the overtravel available through a pin and slot connection of the lever, allowing a striker to hit a bell. Immediately after the motion is stopped by reason of the striker hitting the bell, the bias of the spring moves the lever clockwise about the stop and "takes back" the overtravel in the pin and slot connection and returns the lever to a predetermined position. This takes the striker off the bell immediately after impact and allows the bell to ring clearly whereas the bell would have a dead sound if the striker stayed on the bell. Here, again, is an arrangement of considerable complexity and expense.
It is, therefore, an object of the invention to provide a bell actuating mechanism which is reliable but simpler and less expensive than the mechanisms characteristic of the prior art.
Other objects and advantages of the invention will be apparent from the following description thereof.